Leaving Cert Computer Science: the 2027 exam, the coursework and practice questions

The Leaving Cert Computer Science exam in 2027

The 70 : 30 split is in the NCCA specification. The 2027 changes are in the Assessment Arrangements 2027: JavaScript, HTML and Python are normally all assessed, but in 2027 the written exam tests Python only. In part (b) of Section C you design your own solution to a programming task. The 2027 dates aren't out yet (as of 7 November 2026); in 2026 the written exams ran from 3 to 23 June (Department of Education and Youth).

The Leaving Cert Computer Science coursework

• What you make: a computational artefact, such as a program, simulation or embedded system, plus a report of about 2,500 words on the work and process.
• 2027 timing: 12 school weeks instead of 10, with the brief released in December 2026 and completion in March 2027.
• Focus: it's based on Strand 3. For 2026 to 2027, teachers are told which two of the four applied learning tasks are the main focus, though you can use skills from the others.
• Level: the coursework is common to Higher and Ordinary level.

What Leaving Cert Computer Science covers

• Strand 1, Practices and principles: computational thinking, the design process, and the impact of computing on society.
• Strand 2, Core concepts: abstraction, algorithms (including linear and binary search and sorts such as bubble sort and quicksort), programming with functions including recursion, data types, number systems including binary and hexadecimal, logic gates, and evaluating efficiency.
• Strand 3, Computer science in practice: four applied learning tasks on interactive information systems, analytics, modelling and simulation, and embedded systems.

Grades run from H1 to H8 and O1 to O8, in 10% bands, with CAO points from 100 for an H1 (CAO grading scale).

Leaving Cert Computer Science practice questions

We wrote these for this guide.

1. Python: find the largest value

Question: write a Python function that returns the largest number in a non-empty list, without using max(). Answer: start with the first item and replace it whenever you find something bigger:

def largest(numbers):
    biggest = numbers[0]
    for n in numbers[1:]:
        if n > biggest:
            biggest = n
    return biggest

Starting biggest at 0 would fail for a list of negative numbers. Test it in the Code Editor.

2. Binary search

Question: a sorted list has 1,000 items. What is the most comparisons a binary search needs, and how does that compare with a linear search? Answer: each comparison halves the list, and 2¹⁰ = 1,024 is the first power of 2 above 1,000, so at most 10 comparisons. A linear search could need all 1,000. Binary search only works on sorted data. Count the halvings yourself in our Search Algorithms course and press Mark.

3. Hexadecimal

Question: convert the hexadecimal number 2F to decimal and to 8-bit binary. Answer: 2 × 16 + 15 = 47. Each hex digit is 4 bits: 2 is 0010 and F is 1111, so 2F is 00101111. Check it with the Number Base Converter.

4. Efficiency

Question: why is bubble sort slow for large lists? Answer: it compares neighbouring pairs and may need almost n passes over a list of n items, so the work grows roughly with n². Doubling the list makes it about four times slower. Quicksort usually grows far more slowly. Watch both in the Algorithm Visualiser.

Common mistakes

• Answering every question in Sections A and B in 2027 when you only need 9 and 2.
• Revising JavaScript and HTML for the 2027 exam. Only Python is tested in the written paper.
• Starting values that break edge cases, such as a maximum of 0 for negative data.
• Binary search on unsorted data. Sort first, or use a linear search.

Use a daily paper as a short timed mock

Today's Leaving Cert Computer Science paper covers number representation, data structures, searching and sorting with complexity, recursion, logic, processor architecture, networking and databases. It also includes regular expressions, finite state machines and shortest-path algorithms, which go beyond the Leaving Cert specification. It can't practise the coursework. For when mocks happen, see our Leaving Cert mocks guide.

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